254 THE FEELINGS AND EMOTIONS 
that “the play of youth depends on the fact that certain 
instincts, especially useful in preserving the species, appear 
before the animal seriously needs them.” Does experi- 
mentation occur before it is needed in the economy of animal 
behaviour ? And might we not with equal truth say that the 
play of youth depends on the fact that certain acquired habits, 
especially useful in preserving the species, are gained before 
the animal seriously needs them ? 
Passing now to those forms of play which afford more 
special preparation for particular forms of after-effort, under 
which fall such types as hunting-play and fighting-play, we 
may refer the reader to the copious examples so carefully 
collected by Professor Groos. The way in which a kitten pats 
a cork or a ball, making it roll and then pouncing upon it, is 
a characteristic example of animal play. Valuable as a pre- 
paration for dealing successfully with a mouse when occasion 
shall arise, this is a specialized form of experimentation ; and 
it is more obviously in line with the hunting-behaviour of 
later life than is general experimentation with any particular 
modes of future behaviour. Still it is essentially experimenta- 
tion, with the instinctive propensity setting in more definite 
channels. Its value lies in the acquisition of skill under 
circumstances easier than those presented in the serious chase, 
So, too, in the case of the playful tussles of puppies or in that 
of the kitten, which not only shows playful fight to its 
brothers and sisters, but also to its mother, who responds by 
holding down the struggling and scratching little creature. 
Unquestionably, there is an instinctive propensity ; much of 
the detail, and some of the grouping, exhibit inherited reflexes 
due to special modes of stimulation. No doubt many of these 
responses occur in a similar but more emphatic way in a serious 
fight, and yet we may hesitate before committing ourselves to 
the theory of acceleration. It is at least equally probable 
that play as preparatory behaviour differs in biological detail 
(as it almost certainly does in emotional attributes) from the 
earnest of after-life, and that it was evolved directly as a 
preparation, as a means of experimentation through which 
